CN112834016B - Doppler frequency shift signal processing method and circuit system for laser vibration meter - Google Patents
Doppler frequency shift signal processing method and circuit system for laser vibration meter Download PDFInfo
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- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
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Abstract
The application provides a Doppler frequency shift signal processing method and a circuit system thereof for a laser vibration meter, wherein the signal processing method comprises the following steps: processing the Doppler shift signal based on a first local oscillator signal of a first oscillator through a first mixer to convert the Doppler shift signal into a first mixing signal with preset frequency; filtering the first mixed signal through a first filter to obtain a filtered first mixed signal; processing the filtered first mixed signal based on a second local oscillation signal of a second oscillator through a second mixer so as to convert the first mixed signal into a second mixed signal with preset frequency; filtering the second mixed signal through a second filter to obtain a filtered second mixed signal; performing phase shift processing on the filtered second mixed signal through a phase shifter to obtain a phase-shifted second mixed signal serving as a reference signal; and processing the filtered second mixed signal based on the reference signal through a frequency discriminator to obtain a frequency shift amount therebetween, wherein the frequency shift amount is used for obtaining the vibration signal.
Description
Technical Field
The application relates to the field of laser measurement, in particular to a Doppler frequency shift signal processing method and a circuit system thereof for a laser vibration meter.
Background
The laser vibration meter is also called heterodyne interferometer, dual-frequency interferometer, alternating current interferometer or laser interferometer, and is commonly used for measuring the phase change or Doppler shift of light wave caused by the change of the measured object such as displacement, vibration, rotation or atmospheric disturbance, and the like, and obtaining the displacement, speed or vibration signal of the measured object after demodulation.
The principle of the laser vibration meter is as follows: the laser is divided into two beams under the action of the half-reflecting and half-transmitting glass mirror, one beam is measuring light, and the other beam is reference light, wherein the reference light is modulated by the acousto-optic modulator so as to have a certain frequency shift. The measurement light is focused onto the surface of the measured object and a change in the surface of the measured object causes a doppler shift in the measurement light reflected back to the laser receiver system. The reflected measuring light and the reference light interfere to obtain a light intensity change curve of A sin (wt+phi). Further, the Doppler shift signal is processed by the signal processor, so that the vibration signal of the measured object can be obtained.
The current signal processing circuitry generally processes the doppler shifted signal using high speed digital devices or chips such as high speed ADC (digital to analog converter), FPFA/DSP (digital signal processing), PGC (phase decoding algorithm), and high speed DAC (analog to digital converter) to decode to obtain a vibration signal. The disadvantages of this signal processing circuitry are: the circuit design is complex, the requirement on sampling rate is higher, so that the sampling is carried out by the high-speed ADC chip, the FPFA/DSP algorithm is more complex, the requirement on the circuit design is higher, the cost of the high-speed digital device or chip is more expensive, and the circuit electrically connected with each high-speed digital device/chip is more complex, so that the formed circuit board has larger size and can not realize integrated chip basically.
That is, there is a need in the market for a doppler shift signal processing method and circuitry thereof for a laser vibrometer, which has simple circuitry, low cost, easy integration of chips, and small size.
Disclosure of Invention
One of the main advantages of the present application is to provide a doppler shift signal processing method and its circuit system for a laser vibrometer, which does not need to use high-speed digital devices or chips such as high-speed ADC (digital-to-analog converter), FPFA/DSP (digital signal processing), PGC (phase decoding algorithm), and high-speed DAC (analog-to-digital converter), and has less required circuit elements, simple circuit, low cost, easy integration of chips, and small volume. That is, the circuitry solves the difficulties of the conventional circuitry that the cost is high, the algorithm is complex, and the circuitry cannot be integrated into a chip.
Another advantage of the present application is to provide a doppler shift signal processing method and circuit system for a laser vibrometer, which can demodulate displacement, velocity or vibration signals of a measured object in the presence of strong interference and noise, and improve signal-to-noise ratio, and is suitable for remote measurement or high-speed measurement.
Another advantage of the present application is to provide a doppler shift signal processing method and circuit system for a laser vibrometer, which can directly output an analog vibration signal without conversion processing by a DAC analog-to-digital converter.
Another advantage of the present application is to provide a doppler shift signal processing method and circuit system for a laser vibrometer, which can effectively suppress image interference and improve measurement sensitivity.
The application also has the advantages of providing a Doppler frequency shift signal processing method for the laser vibration meter and a circuit system thereof, wherein the circuit is simple to implement, stable and reliable, low in cost and wide in application range.
Other advantages and features of the present application will become more fully apparent from the following detailed description, and may be learned by the practice of the application as set forth hereinafter.
According to one aspect of the present application, there is provided a doppler shift signal processing method for a laser vibrometer for measuring a vibration signal of a measured object, including:
processing the Doppler shift signal based on a first local oscillator signal of a first oscillator through a first mixer to convert the Doppler shift signal into a first mixing signal with preset frequency;
filtering the first mixed signal through a first filter to obtain a filtered first mixed signal;
processing the filtered first mixed signal based on a second local oscillation signal of a second oscillator through a second mixer so as to convert the first mixed signal into a second mixed signal with preset frequency;
filtering the second mixed signal through a second filter to obtain a filtered second mixed signal;
performing phase shift processing on the filtered second mixed signal through a phase shifter to obtain a phase-shifted second mixed signal serving as a reference signal; and
and processing the filtered second mixed signal based on the reference signal through a frequency discriminator to obtain a frequency shift amount between the second mixed signal and the reference signal, wherein the frequency shift amount is used for obtaining the vibration signal.
In an embodiment of the application, a bandwidth of the first filter is consistent with a preset frequency of the first mixing signal, wherein a bandwidth of the second filter is consistent with the preset frequency of the second mixing signal.
In an embodiment of the present application, the reference signal is orthogonal to the second mixing signal in the same frequency, wherein the frequency discriminator is a quadrature frequency discriminator.
In an embodiment of the present application, after filtering the second mixed signal by a second filter to obtain a filtered second mixed signal, before performing phase shift processing on the filtered second mixed signal by a phase shifter to obtain a phase-shifted second mixed signal as a reference signal, the method includes:
amplifying the filtered second mixed signal.
According to another aspect of the present application, there is also provided a doppler shift signal processing circuitry for a laser vibrometer for measuring a vibration signal of a measured target, the circuitry comprising:
a first oscillator for providing a first local oscillator signal;
the first mixer is used for processing the Doppler frequency shift signal based on a first local oscillation signal of the first oscillator so as to convert the Doppler frequency shift signal into a first mixing signal with preset frequency;
a first filter, configured to perform filtering processing on the first mixed signal, so as to obtain a filtered first mixed signal;
a second oscillator for providing a second local oscillator signal;
the second mixer is used for processing the filtered first mixing signal based on a second local oscillation signal of the second oscillator so as to convert the first mixing signal into a second mixing signal with preset frequency;
a second filter, configured to perform filtering processing on the second mixed signal, so as to obtain a filtered second mixed signal;
the phase shifter is used for carrying out phase shifting processing on the filtered second mixed signal so as to obtain a phase-shifted second mixed signal as a reference signal; and
and the frequency discriminator is used for processing the filtered second mixed signal based on the reference signal so as to obtain a frequency shift amount between the second mixed signal and the reference signal, wherein the frequency shift amount is used for acquiring the vibration signal.
In an embodiment of the application, a bandwidth of the first filter is consistent with a preset frequency of the first mixing signal, wherein a bandwidth of the second filter is consistent with the preset frequency of the second mixing signal.
In an embodiment of the present application, the reference signal is orthogonal to the second mixing signal in the same frequency, wherein the frequency discriminator is a quadrature frequency discriminator.
In an embodiment of the application, the circuit system further includes an amplifier, wherein the amplifier is configured to amplify the filtered second mixing signal and input to the phase shifter and the frequency discriminator, respectively.
According to another aspect of the present application, there is also provided a doppler shift signal processing circuit chip for a laser vibrometer for measuring a vibration signal of a measured object, the circuit chip integrating a first mixer, a first oscillator, a first filter, a second mixer, a second oscillator, a second filter, a phase shifter, and a frequency discriminator, wherein,
the first oscillator is used for providing a first local oscillator signal;
the first mixer is configured to process the doppler shift signal based on a first local oscillation signal of a first oscillator, so as to convert the doppler shift signal into a first mixing signal with a preset frequency;
the first filter is configured to perform filtering processing on the first mixed signal to obtain a filtered first mixed signal;
the second oscillator is used for providing a second local oscillation signal;
the second mixer is configured to process the filtered first mixing signal based on a second local oscillation signal of a second oscillator, so as to convert the first mixing signal into a second mixing signal with a preset frequency;
the second filter is configured to perform filtering processing on the second mixed signal to obtain a filtered second mixed signal;
the phase shifter is used for carrying out phase shifting treatment on the filtered second mixed signal so as to obtain a phase-shifted second mixed signal as a reference signal; and
the frequency discriminator is configured to process the filtered second mixed signal based on the reference signal, so as to obtain a frequency shift amount between the two signals, where the frequency shift amount is used to obtain the vibration signal.
In one embodiment of the present application, the circuit chip is a 24-pin dual in-line integrated chip.
Further objects and advantages of the present application will become fully apparent from the following description and the accompanying drawings.
These and other objects, features and advantages of the present application will become more fully apparent from the following detailed description, the accompanying drawings and the appended claims.
Drawings
Fig. 1 illustrates a block diagram of doppler shift signal processing circuitry for a laser vibrometer in accordance with a preferred embodiment of the present application.
Fig. 2 illustrates a schematic diagram of a circuit chip of a specific example of the circuit system according to the preferred embodiment of the present application.
Fig. 3 illustrates an integrated circuit schematic diagram of a specific example of the circuitry according to the preferred embodiment of the present application.
Fig. 4 illustrates a flow chart of a doppler shift signal processing method for a laser vibrometer according to a preferred embodiment of the present application.
Detailed Description
The following description is presented to enable one of ordinary skill in the art to make and use the application. The preferred embodiments in the following description are by way of example only and other obvious variations will occur to those skilled in the art. The basic principles of the application defined in the following description may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the application.
It will be appreciated by those skilled in the art that in the present disclosure, the terms "longitudinal," "transverse," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," etc. refer to an orientation or positional relationship based on that shown in the drawings, which is merely for convenience of description and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore the above terms should not be construed as limiting the present application.
It will be understood that the terms "a" and "an" should be interpreted as referring to "at least one" or "one or more," i.e., in one embodiment, the number of elements may be one, while in another embodiment, the number of elements may be plural, and the term "a" should not be interpreted as limiting the number.
Exemplary circuitry
Fig. 1 shows a block diagram schematic of signal processing circuitry for a laser vibrometer according to a preferred embodiment of the application, as shown in fig. 1, the circuitry according to the preferred embodiment of the application comprising: the first mixer 10, the first oscillator 11, the first filter 20, the second mixer 30, the second oscillator 31, the second filter 40, the phase shifter 50, and the frequency discriminator 60 are used for performing a processing function of measuring a doppler shift signal obtained by a measured object by a laser vibrometer as described below.
The first mixer 10 is configured to be communicatively or electrically connected to the laser vibrometer, where the first mixer 10 is configured to perform a mixing process on the doppler shift signal based on the first local oscillator signal of the first oscillator 11 to convert the doppler shift signal into a first mixing signal with a preset frequency. It may be appreciated that the first local oscillator signal is an internal local oscillator frequency or a local oscillator frequency of the first oscillator 11, where the frequency of the first local oscillator signal may be preset or adjusted, where the first local oscillator signal of the first oscillator 11 is input to the first mixer 10, where the first mixer 10 converts the doppler shift signal into an output signal with a preset frequency based on the first local oscillator signal, that is, the first mixing signal.
The first oscillator 11 is communicatively and/or electrically connected to the first mixer 10, wherein the first oscillator 11 is configured to generate a first local oscillator signal and input to the first mixer 10, wherein the first oscillator 11 may be a voltage controlled oscillator.
Further, the frequency of the first mixing signal is the sum or difference of the frequencies of the first local oscillation signal and the Doppler shift signal. The frequency of the first local oscillator signal can be preset or adjusted on a certain working frequency band to obtain an output signal with a corresponding frequency, namely the first mixing signal. Optionally, the preset frequency of the first mixing signal is about 10.7MHz, or a frequency of other range value. For example, when the high-speed measurement, that is, the vibration or moving speed of the measured object is large, according to the doppler formula Δf=2v/λ, λ=632.8 nm, if the doppler shift signal is 40MHz, the frequency of the first local oscillator signal should be 40MHz-10.7 mhz=29.3 MHz, and after the mixing processing, the first mixed signal with the frequency of 10.7MHz is obtained. As is well known to those skilled in the art, the first mixing signal may be an intermediate frequency signal of a specific frequency.
The first filter 20 is communicatively or electrically connected to the first mixer 10, wherein the first filter 20 is configured to filter the first mixed signal to obtain a filtered first mixed signal. The filtering bandwidth of the first filter 20 may be preset to obtain the first mixing signal with the desired frequency, suppress other frequency components (i.e. suppress interference and noise), and improve the signal-to-noise ratio. For example, the bandwidth of the first filter 20 is preset to 10.7MHz to obtain the first mixing signal of 10.7MHz, and other frequency components are suppressed to improve measurement accuracy. That is, the bandwidth of the first filter substantially coincides with the preset frequency of the first mixing signal.
Optionally, the first filter 20 is a narrow-band filter, further an ultra-narrow-band crystal filter, and the ratio of its center frequency to its bandwidth (i.e. Q value) is high, that is, the center frequency of the first filter 20 is generally a constant value, and the higher the Q value is, the narrower the bandwidth of the first filter 20 is, so as to suppress a large amount of interference and noise, so that the circuit system can successfully demodulate a required vibration signal in the presence of strong interference and noise.
In the present application, since the doppler shift signal is first mixed by the first mixer 10 to obtain the first mixed signal with the preset frequency, and then the first filter 20 performs the narrow-band filtering processing on the first mixed signal, the bandwidth of the first filter 20 can be set narrower, that is, the Q value is higher, so that the signal-to-noise ratio is greatly improved, and the method is suitable for long-distance (such as greater than 50 meters) measurement or high-speed (such as greater than 1 m/s) measurement. Which is not possible with software algorithms or filters in the signal processing circuitry of conventional laser vibrometers.
The second mixer 30 is communicatively and/or electrically connected to the first filter 20, and processes the filtered first mixing signal by the second mixer 30 based on a second local oscillator signal of the second oscillator 31 to transform the first mixing signal into a second mixing signal of a preset frequency. The second local oscillation signal is an internal local oscillation frequency or a local oscillation frequency of the second oscillator 31, where the frequency of the second local oscillation signal may be preset or adjusted, and the second mixer 30 converts the first mixing signal into an output signal with a preset frequency based on the second local oscillation signal, that is, the second mixing signal.
Further, the frequency of the second mixing signal is the sum or difference of the frequencies of the second local oscillation signal and the first mixing signal. The frequency of the second local oscillator signal can be preset or adjusted on a certain working frequency band to obtain an output signal with a corresponding frequency, namely the second mixing signal. Optionally, the preset frequency of the second mixing signal is 455KHz or about 500KHz, or a frequency with other range values. As is well known to those skilled in the art, the second mixing signal may be an intermediate frequency signal of a specific frequency.
The second oscillator 31 is communicatively and/or electrically connected to the second mixer 30, wherein the second oscillator 31 is configured to generate a second local oscillator signal and input to the second mixer 10, wherein the second oscillator 31 may be a voltage controlled oscillator.
The second filter 40 is connected to the second mixer 30 in a manner of being connectable and/or electrically connected, wherein the second filter 40 is configured to filter the second mixed signal to obtain the filtered second mixed signal. The filtering bandwidth of the second filter 40 may be preset to obtain the second mixing signal with the desired frequency, suppress other frequency components (i.e. suppress interference and noise), improve the signal-to-noise ratio, and suppress the image interference. For example, the bandwidth of the second filter 40 is preset to 455kHz or around 500kHz to obtain the second mixing signal of the corresponding frequency, and suppress other frequency components, and suppress image interference to improve measurement accuracy. That is, the bandwidth of the second filter 40 substantially coincides with the preset frequency of the second mixing signal.
Optionally, the second filter 40 is a narrowband filter, further is an ultra-narrowband crystal filter, and the ratio of the center frequency to the bandwidth (i.e. Q value) is higher, that is, the center frequency of the second filter 40 is generally a fixed value, and the higher the Q value is, the narrower the bandwidth of the second filter 40 is, so as to suppress a large amount of interference and noise, so that the circuit system can successfully demodulate the required vibration signal in the presence of strong interference and noise.
It should be noted that the circuit system adopts the double frequency conversion circuits of the first mixer 10, the first filter 20, the second mixer 30 and the second filter 40, which not only suppresses interference and noise of other frequency components, but also suppresses image interference, improves sensitivity, effectively improves measurement accuracy, and is suitable for long-distance or high-speed measurement. Which is not possible with software algorithms or filters in the signal processing circuitry of conventional laser vibrometers.
The phase shifter 50 is communicatively and/or electrically connected to the second filter 40, wherein the phase shifter 50 is configured to perform a phase shift process on the filtered second mixing signal to obtain a phase-shifted second mixing signal as a reference signal, i.e. the reference signal has a certain phase difference with the filtered second mixing signal. The frequency discriminator 60 is communicatively and/or electrically connected to the second filter 40 and the phase shifter 50, wherein the frequency discriminator 60 is configured to process the filtered second mixing signal based on the reference signal (i.e., the phase-shifted second mixing signal) to obtain a frequency shift amount therebetween, wherein the frequency shift amount is used to obtain a vibration signal of a measured object.
It can be understood that the second mixed signal phase-shifted by the phase shifter 50 and the second mixed signal filtered by the second filter 40 are used as input signals of the frequency discriminator 60, wherein the frequency discriminator 60 outputs a frequency shift difference, i.e., a frequency shift amount, between the two signals. That is, the second mixing signal filtered by the second filter 40 is divided into two paths, one path is processed by the phase shifter 50 and then is input to the frequency discriminator 60 as the reference signal, the other path is directly input to the frequency discriminator 60, and the frequency shift amount is generated by the frequency discriminator 60 to obtain the vibration signal through demodulation.
The phase shifter 50 performs phase adjustment on the filtered second mixing signal, and a value of the adjusted phase of the second mixing signal may be preset, preferably, after the phase shifter 50 processes the second mixing signal, the reference signal is orthogonal to the phase of the filtered second mixing signal, that is, the reference signal is orthogonal to the filtered second mixing signal in the same frequency. Preferably, the frequency discriminator 60 is a quadrature frequency discriminator, which is a product phase frequency discriminator, the frequency discriminator 60 includes a multiplier and a low-pass filter, wherein the filtered second mixing signal and the phase-shifted second mixing signal are added to the multiplier together, and the low-pass filter filters the second mixing signal to output a voltage signal of the frequency shift, that is, the voltage signal of the frequency shift represents displacement, velocity or vibration information of the measured object, so as to obtain the vibration signal by demodulation. It can be seen that the frequency shift amount output by the frequency discriminator 60 is an analog voltage signal, and the conversion processing by the DAC analog-to-digital converter is not needed, i.e. the circuit system can directly output an analog vibration signal, and the conversion processing by the DAC analog-to-digital converter is not needed.
Further, the circuit system further comprises an amplifier 70, wherein the amplifier 70 is communicatively and/or electrically connected between the second filter 40 and the phase shifter 50 and the frequency discriminator 60, wherein the amplifier 70 is configured to amplify the filtered second mixing signal, wherein the amplified second mixing signal is input to the phase shifter 50 and the frequency discriminator 60, respectively, to improve the sensitivity and detection accuracy of the circuit system. The amplifier 70 is a low noise amplifier, which suppresses interference of other frequency components and reduces noise while amplifying a signal.
Further, the circuitry may further comprise an input circuit 80, wherein the input circuit 80 is communicatively and/or electrically connected to the first mixer 10, wherein the Doppler shifted signal is matched to the first mixer 10 via the input circuit 80 to increase sensitivity. The input circuit 80 may be an input matching network, and the doppler shift signal received by the laser vibrometer is matched and input to the first mixer 10 through the input circuit 80, so that the circuitry can demodulate the doppler shift signal and output the vibration information. The doppler shift signal may be a radio frequency signal or an FM signal, and the input circuit 80 inputs the corresponding doppler shift voltage signal to the first mixer 10 in a matching manner, so as to achieve matching input and processing of signals.
Further, the circuit system further includes a filter, where the filter is communicatively and/or electrically connected to the frequency discriminator 60, and the filter is configured to filter the voltage signal of the frequency quantity output by the frequency discriminator 60 to obtain the frequency shift quantity after filtering, so as to demodulate according to the frequency shift quantity after filtering to obtain the vibration information, so as to further filter clutter interference, reduce noise, and improve signal to noise ratio.
It should be noted that the circuit system may further include a limiter for performing a clipping process on the signal, where the limiter is a circuit for clipping the voltage amplitude of the signal according to a limited range, that is, the limiter is used to limit the amplitude of the voltage signal within a certain range, so as to remove the interference at the top or bottom of the output waveform, and also plays a role in protecting the circuit system.
As shown in fig. 2 and 3, a circuit chip of the circuit system is further provided in this embodiment, and the circuit chip is used to integrate the first mixer 10, the first oscillator 11, the first filter 20, the second mixer 30, the second oscillator 31, the second filter 40, the phase shifter 50, and the frequency discriminator 60, where the circuit chip is used as an integrated circuit of the circuit system. The circuit system does not need to adopt high-speed digital devices or chips such as high-speed ADC (digital-to-analog converter), FPFA/DSP (digital signal processing), PGC (phase decoding algorithm), high-speed DAC (analog-to-digital converter) and the like, and all components can be integrated on the circuit chip, so that the circuit system has smaller volume. That is, the circuitry solves the difficulties of the conventional circuitry that the cost is high, the algorithm is complex, and the circuitry cannot be integrated into a chip.
For example, the circuit chip is a 24-pin dual in-line integrated chip having 24 pins, wherein pins 1 and 24 are pins of the input of the first mixer 10, wherein the Doppler shift signal is input by the input circuit 80 to pin 1 (i.e., the input of the first mixer 10) in a matched manner, wherein pin 24 is grounded through capacitive coupling. The pin 2 is a pin of the second local oscillator signal output end of the second oscillator 31, the pin 3 is a pin of the second local oscillator signal emitter of the second oscillator 31, the pin 4 is a pin of the second local oscillator signal base of the second oscillator 31, and the pin 5 is a pin of the output end of the second mixer 30, for outputting the second mixing signal. Pin 6 is the pin at the positive power supply terminal (Vcc) and pin 16 is the pin at the negative power supply terminal (Vee). The pin 7 is the pin of the input end of the amplitude limiter, and the pin 8 and the pin 9 are the pins decoupled from the amplitude limiter. And the 10 pins are pins of an ammeter display driving indication end. And 11 pins are pins of the carrier detection end of the second mixing signal. The 12 pin is a pin of the access end of the phase shifter 50, and the phase shifter 50 may be externally connected to the 12 pin. And 13 pins are pins at the output end of the circuit system and are used for outputting the demodulated vibration signals. The 14 pin is a pin of the input end of the frequency discriminator 60, and the 15 pin is a pin of the output end of the frequency discriminator 60. Pins 17 and 18 are pins at the input of the second mixer 30, and pin 19 is a pin at the output of the first mixer 10. The pin 20 is a pin of the output end of the first oscillator 11, the pins 21 and 22 are pins of the first local oscillator signal resonant circuit of the first oscillator 11, and the pin 23 is a pin of the varactor control end of the first oscillator 11.
Exemplary Signal processing method for heterodyne laser interferometer
Fig. 4 is a flow chart of a method for processing doppler shift signals of a laser vibrometer according to a preferred embodiment of the present application. The laser vibrometer is used for measuring detection data such as displacement signals or vibration signals of a measured object, as shown in fig. 4, and the signal processing method according to the preferred embodiment of the application includes:
processing, by the first mixer 10, the doppler shift signal based on the first local oscillator signal of the first oscillator 11 to convert the doppler shift signal into a first mixed signal with a preset frequency;
filtering the first mixed signal through the first filter 20 to obtain a filtered first mixed signal;
processing the filtered first mixed signal by a second mixer 30 based on a second local oscillation signal of a second oscillator 31 to convert the first mixed signal into a second mixed signal with a preset frequency;
filtering the second mixed signal through a second filter 40 to obtain a filtered second mixed signal;
performing phase shift processing on the filtered second mixed signal through a phase shifter 50 to obtain a phase-shifted second mixed signal as a reference signal; and
the filtered second mixed signal is processed by a frequency discriminator 60 based on the reference signal to obtain a frequency shift amount therebetween, wherein the frequency shift amount is used to obtain the vibration signal.
In an embodiment of the present application, in the signal processing method, a bandwidth of the first filter is consistent with a preset frequency of the first mixing signal, and a bandwidth of the second filter is consistent with the preset frequency of the second mixing signal.
In an embodiment of the present application, in the signal processing method, the reference signal is orthogonal to the second mixing signal in a same frequency, wherein the frequency discriminator is a quadrature frequency discriminator.
In an embodiment of the present application, the signal processing method, after filtering the second mixed signal by the second filter 40 to obtain the filtered second mixed signal, includes, before performing phase shifting processing on the filtered second mixed signal by the phase shifter 50 to obtain the phase-shifted second mixed signal as a reference signal: amplifying the filtered second mixed signal.
The basic principles of the present application have been described above in connection with specific embodiments, however, it should be noted that the advantages, benefits, effects, etc. mentioned in the present application are merely examples and not intended to be limiting, and these advantages, benefits, effects, etc. are not to be considered as essential to the various embodiments of the present application. Furthermore, the specific details disclosed herein are for purposes of illustration and understanding only, and are not intended to be limiting, as the application is not necessarily limited to practice with the above described specific details.
The block diagrams of the devices, apparatuses, devices, systems referred to in the present application are merely illustrative examples and are not intended to require or imply that the connections, arrangements, configurations must be made in the manner shown in the block diagrams. As will be appreciated by one of skill in the art, the devices, apparatuses, devices, systems may be connected, arranged, configured in any manner. Words such as "including," "comprising," "having," and the like are words of openness and mean "including but not limited to," and are used interchangeably therewith. The terms "or" and "as used herein refer to and are used interchangeably with the term" and/or "unless the context clearly indicates otherwise. The term "such as" as used herein refers to, and is used interchangeably with, the phrase "such as, but not limited to.
It is also noted that in the apparatus, devices and methods of the present application, the components or steps may be disassembled and/or assembled. Such decomposition and/or recombination should be considered as equivalent aspects of the present application.
The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the application. Thus, the present application is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
It will be appreciated by persons skilled in the art that the embodiments of the application described above and shown in the drawings are by way of example only and are not limiting. The objects of the present application have been fully and effectively achieved. The functional and structural principles of the present application have been shown and described in the examples and embodiments of the application may be modified or practiced without departing from the principles described.
Claims (7)
1. A doppler shift signal processing method for a laser vibrometer for measuring a vibration signal of a measured object, comprising:
processing the Doppler shift signal based on a first local oscillator signal of a first oscillator through a first mixer to convert the Doppler shift signal into a first mixing signal with preset frequency;
filtering the first mixed signal through a first filter to obtain a filtered first mixed signal, wherein the first filter is a narrow-band filter;
processing the filtered first mixed signal based on a second local oscillation signal of a second oscillator through a second mixer so as to convert the first mixed signal into a second mixed signal with preset frequency;
filtering the second mixed signal through a second filter to obtain a filtered second mixed signal, wherein the second filter is a narrow-band filter;
performing phase shift processing on the filtered second mixed signal through a phase shifter to obtain a phase-shifted second mixed signal serving as a reference signal; and
processing the filtered second mixing signal based on the reference signal by a frequency discriminator to obtain a frequency shift amount between the second mixing signal and the reference signal, wherein the frequency shift amount is used for obtaining the vibration signal, and the frequency shift amount output by the frequency discriminator is a voltage signal of analog quantity and does not need conversion processing by a DAC analog-to-digital converter; the reference signal is orthogonal to the second mixing signal in the same frequency, the frequency discriminator is a quadrature frequency discriminator, and the frequency discriminator comprises a multiplier and a low-pass filter.
2. The signal processing method of claim 1, wherein a bandwidth of the first filter coincides with a preset frequency of the first mixing signal, wherein a bandwidth of the second filter coincides with the preset frequency of the second mixing signal.
3. The signal processing method according to any one of claims 1 to 2, wherein after filtering the second mixed signal by a second filter to obtain the filtered second mixed signal, before phase-shifting the filtered second mixed signal by a phase shifter to obtain the phase-shifted second mixed signal as a reference signal, comprising:
amplifying the filtered second mixed signal.
4. Doppler shift signal processing circuitry for a laser vibrometer for measuring a vibration signal of a measured target, the circuitry comprising:
a first oscillator for providing a first local oscillator signal;
the first mixer is used for processing the Doppler frequency shift signal based on a first local oscillation signal of the first oscillator so as to convert the Doppler frequency shift signal into a first mixing signal with preset frequency;
the first filter is used for carrying out filtering processing on the first mixed signal so as to obtain a filtered first mixed signal, and the first filter is a narrow-band filter;
a second oscillator for providing a second local oscillator signal;
the second mixer is used for processing the filtered first mixing signal based on a second local oscillation signal of the second oscillator so as to convert the first mixing signal into a second mixing signal with preset frequency;
the second filter is used for carrying out filtering processing on the second mixed signal so as to obtain a filtered second mixed signal, and the second filter is a narrow-band filter;
the phase shifter is used for carrying out phase shifting processing on the filtered second mixed signal so as to obtain a phase-shifted second mixed signal as a reference signal; and
the frequency discriminator is used for processing the filtered second mixed signal based on the reference signal to obtain a frequency shift quantity between the second mixed signal and the reference signal, wherein the frequency shift quantity is used for obtaining the vibration signal, the frequency shift quantity output by the frequency discriminator is a voltage signal of analog quantity, conversion processing by a DAC analog-to-digital converter is not needed, the reference signal is orthogonal with the second mixed signal in the same frequency, the frequency discriminator is an orthogonal frequency discriminator, and the frequency discriminator comprises a multiplier and a low-pass filter.
5. The circuitry of claim 4, wherein a bandwidth of the first filter is consistent with a preset frequency of the first mixing signal, wherein a bandwidth of the second filter is consistent with a preset frequency of the second mixing signal.
6. The circuitry of any of claims 4 to 5, further comprising an amplifier, wherein the amplifier is configured to amplify the filtered second mixed signal and input to the phase shifter and the frequency discriminator, respectively.
7. A Doppler frequency shift signal processing circuit chip for a laser vibrometer, wherein the laser vibrometer is used for measuring a vibration signal of a measured object, and the circuit chip is integrated with a first mixer, a first oscillator, a first filter, a second mixer, a second oscillator, a second filter, a phase shifter and a frequency discriminator, wherein,
the first oscillator is used for providing a first local oscillator signal;
the first mixer is configured to process the doppler shift signal based on a first local oscillation signal of a first oscillator, so as to convert the doppler shift signal into a first mixing signal with a preset frequency;
the first filter is configured to perform filtering processing on the first mixed signal to obtain a filtered first mixed signal, where the first filter is a narrowband filter;
the second oscillator is used for providing a second local oscillation signal;
the second mixer is configured to process the filtered first mixing signal based on a second local oscillation signal of a second oscillator, so as to convert the first mixing signal into a second mixing signal with a preset frequency;
the second filter is configured to perform filtering processing on the second mixed signal to obtain a filtered second mixed signal, where the second filter is a narrowband filter;
the phase shifter is used for carrying out phase shifting treatment on the filtered second mixed signal so as to obtain a phase-shifted second mixed signal as a reference signal; and
the frequency discriminator is configured to process the filtered second mixed signal based on the reference signal to obtain a frequency shift amount therebetween, where the frequency shift amount is used to obtain the vibration signal, the frequency shift amount output by the frequency discriminator is a voltage signal of an analog quantity, conversion processing by a DAC analog-to-digital converter is not required, the reference signal is orthogonal to the second mixed signal in the same frequency, the frequency discriminator is an orthogonal frequency discriminator, and the frequency discriminator includes a multiplier and a low-pass filter; the circuit chip is a 24-pin dual in-line integrated chip.
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